Genetics problem?

Question

   A horse’s coat color is controlled by many different gene pairs. A dominant B will give the horse a black color, and a b will give the horse a chestnut color. However, when a dominant W is present in the second gene pair, the horse will be white no matter what. If the second gene pair is ww, then the horse will be the color of whatever the first gene pair is made of.

Horses can also be bay in color. This dominant gene allele (A) masks the dominant black color, but not the white gene or the recessive chestnut color. What is the phenotype and genotype of the offspring when a bay mare (AaBBww) is crossed with a bay stallion (AaBbww)?

 Horses also carry a dilution gene (D). If only one allele is the dominant D, and a dominant A allele and the recessive chestnut color genes are present, then the horse will be a palamino. If there are two dominant dilution alleles (DD) and all else is the same as previously mentioned, the horse will be a pseudo albino. What is the phenotype and genotype of the offspring when a palomino mare (AAbbDdww) is crossed with a palomino stallion (AabbDdww)?

-- not really familiar on identifying the genotype and phenotype when it comes to crosses of multiple traits. Was able to get the punnet square done but dont know were to go from there.

Answer 1

I think that you are still working only with one trait - color - even with all these alleles. Just keep track of what each part means, and check off every contribution one by one of A, B, D, and W, and the combos mentioned.

If you did the punnet square you have got the genotype fine. The phenotype is the harder part in this case.

For example if I make a random genotype:

AaBbwwDd

First, is there a dominant W, which means it is white? - ww - no.

Is the B gene consistent with the horse being black? - Bb - yes.

BUT, is there a dominant A gene, which masks the horse being black and makes it bay colored? - Aa - yes.

Is there a dominant D, dominant A, and recessive bb chestnut? yes for the first two, no for the last. So - no.

Therefore, that example was a bay colored horse.

Basically you make a flow chart.

1. Is there any copy of dominant W (WW or Ww)?
2. If yes, you're done. The horse is white.
3. If no, go to 2.
4. Does it have a dominant BB or Bb configuration?
5. Does it have an AA or Aa genotype?
6. Yes on #2 + yes on #3, the horse is bay colored.
7. Yes on #2 + no on #3, the horse is black.
8. If no on #2 and no on #3, the horse is chestnut.
9. If no on #2 and yes on #3, continue to 4.
10. Check the horse's D genotype.
11. If Dd, the horse is palomino.
12. If DD, the horse is pseudo albino.
13. If dd, the horse is chestnut.